Vascular sheath

ABSTRACT

Disclosed is a vascular sheath for helping to prevent bleeding during procedures in which devices must be inserted into a blood vessel such as an artery or vein. The vascular sheath includes at least one manually compressible primary seal that has a lumen passing therethrough. A device inserted into the blood vessel first passes through the sheath, and thus through the lumen in the primary seal. By manually adjusting the compression of the primary seal the size of at least part of the lumen is made to substantially conform to the outer surface of the device. The primary seal can thus seal against large and small sized devices to prevent bleeding. It is preferred that a secondary seal also be used and one type of secondary seal is a flexible disk or flap with one or more slits through which the device passes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 11/042,472 also entitled “VASCULAR SHEATH”, filedon Jan. 24, 2005, which application claims priority to U.S. ProvisionalApplication Ser. No. 60/538,712, filed Jan. 23, 2004, by inventor JohnC. Opie, both of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to medical systems and methods, and moreparticularly, to a vascular sheath to assist in preventing excessivebleeding during certain medical procedures.

BACKGROUND OF THE INVENTION

This invention relates to vascular sheaths (preferably larger diametersheaths) having an improved hemostatic valve or gasket assembly toassist in preventing excessive bleeding when the sheath is “dormant.”“Dormant” in this context means that the sheath is temporarilytransmitting and/or retaining a small diameter secondary device such asa medical guide wire (also referred to herein as a guide wire or wire),or diagnostic catheters for procedures such as serial angiograms.

Vascular sheaths (also referred to herein as a sheath or vascular accesssheath) are delivery platforms used to introduce secondary devices intoblood vessels. These secondary devices include, for example, dilators,guide wires, angioplasty balloons, stents, atherectomy catheters,angiography catheters and abdominal aortic aneurysm endo-luminal grafts.The sheaths usually range from a diameter of about 5-French to 24-French(“Fr”) depending upon the size of the secondary device. The upper limitis dictated to some extent by human anatomy, particularly the size ofthe femoral artery.

Known sheaths work relatively well and are substantially hemostatic whenused with relatively large indwelling secondary devices. However, whenknown sheaths are used with a relatively small diameter secondarydevice, such as a guide wire, they typically leak sizable quantities ofblood. This is due to the efficiency of the cruciate slits typicallyfound in the elastomeric (usually a silicone rubber) gasket that is usedin known sheaths to form a seal. Using the example of a guide wire, thewire tends to slip into one of the slits creating a small eye-shapedopening in the slit and bleeding occurs through the opening. Because ofthis, it is common to put a second sheath, usually of 10-Frenchdiameter, over the wire and into the larger sheath to create a seal andstop the bleeding. In some instances a glob of wax is used to plug theend of the sheath.

One solution to this problem has been suggested by the Touhey-Borstsystem, which is known in the art. However, that system does not performwell when large bore secondary devices (such as large bore obdurators)are removed from large bore sheaths and only wires or catheters remain.The Touhey-Borst valve construction includes an O-ring seal that iscompressed during use. However, the O-ring is contained staticallywithin the distal end of a second chamber. Such a mechanism is unable toseal a large bore secondary device, and after the large device isremoved, then seal down against a small diameter secondary device, suchas a wire or angiocatheter. This is due to the fact that only so muchcompression is available with the non-moving O-ring.

Other methods have been developed to solve this problem and have notbeen entirely successful. Some sheaths include two or even threeelastomeric gaskets, but blood still leaks when only the wire passesthrough the sheath. Other sheaths include torroidal balloons. Torroidalballoons may work but are cumbersome and when a large secondary deviceis removed from the sheath one must quickly inflate the balloon with asyringe to avoid a sudden and large blood loss via the large openingthrough the balloon.

Other devices have suggested iris-type valve assemblies, but these havenot been widely used due to the expense of making them and the potentialproblem of engaging them or disengaging them with resultant transienttorrential femoral artery bleeding. Still other inventors have devisedflapper valve mechanisms.

SUMMARY OF THE INVENTION

The invention is a vascular sheath that permits the passage of asecondary device into a blood vessel, such as the femoral artery. Inaccordance with the present invention, an improved vascular accesssheath is provided to facilitate the introduction of both large andsmall diameter secondary devices into a vein or artery, while assistingto prevent significant blood loss, even when the sheath only transmits arelatively small secondary device, such as a medical guide wire.

The sheath includes a body and a primary seal retained in the housing.The primary seal has a lumen passing therethrough and the secondarydevice passes through the lumen. As the primary seal is compressed(which is preferably done by tightening a cap on the body, wherein thecap is attached to a post that presses against the primary seal) atleast part of the lumen is compressed and substantially presses againstthe outer surface of the secondary device to form a seal. In thismanner, the sheath can seal against both relatively large diameterdevices and relatively small diameter devices.

The sheath also preferably includes one or more secondary seals. Thepreferred secondary seal is a flexible disk having one or more slitsthrough which the secondary device can pass.

A vascular access sheath according to the invention is preferably is alarge bore vascular access sheath of a size between 5 Fr and 24 Fr.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention as claimed.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one or more preferred embodimentsof the invention and together with the description, serve to explain theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional, side view of a cap for a vascular sheathaccording to the invention.

FIG. 2 is a top view of the cap of FIG. 1.

FIG. 3 is a partial cross-sectional, side view of a primary seal for asheath according to the invention.

FIG. 4 is a cross-sectional, side view of a body of a vascular sheathaccording to the invention.

FIG. 5 is a side view of a secondary device that may be used with theinvention.

FIG. 6 is a cross-sectional, side view of a vascular sheath according tothe invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred exemplaryembodiments of the invention, examples of which are illustrated in theaccompanying drawings.

As used herein, “distal” refers to being more distant to the operator(usually a surgeon) and closer to the interior of the patient's bloodvessel, wherein “proximal” means closer to the operator and further fromthe interior of the patient's blood vessel.

FIG. 1 is a cross-sectional, side view of a cap 1 showing a central post6 and an enclosed thread 4 to threadibly engage a matching thread ofbody 30 of the vascular sheath 100 (see FIG. 6). The purpose of cap 1 isto seal sheath 100 and, in particular, to compress primary seal (orO-ring) 20, and any suitable structure may be used for this purpose. Inthis embodiment cap 1 is generally circular in shape.

Cap 20 is preferably comprised of injection molded plastic such aspolyethylene, polypropylene or vinyl, but may be of any suitablematerial and manufactured using any suitable technique.

Central post 6 extends outward and has a flange or ridge 7 to whichsecondary seal 8 is preferably attached. Cap 1 has a distal end 1 A anda proximal end 2. Wall 3 of cap 1 and enclosed thread 4 are designed toengage a matching thread 37 of body 30, which is best seen in FIG. 6.

A central lumen 5 of post 6 extends from the base of cap 1 to the distalend of cap 1. Lumen 5 of post 6 is large enough to permit the passage ofa secondary device, such as a large obdurator, an example of which isshown in FIG. 5. Bore 5 may have a diameter of, for example, 16 Fr, 18Fr, 20 Fr, 22Fr, or 24 Fr. A secondary seal, as shown, is gasket 8,which has a slit or slits or other opening through which the secondarydevice may pass. Gasket 8 is preferably made of elastomeric siliconerubber although any suitable material may be used. In order to housegasket 8, proximal end 2 of cap 1 has a chamber 10 that receives gasket8. Chamber 10 is preferably permanently closed once gasket 8 ispositioned therein, but could be formed to open so that gasket 8 couldbe removed and changed. Angled edge 11 of cap 1 is optional and assiststo facilitate centering of a secondary device (not shown in this Figure)passed through cap 1.

FIG. 2 is a top view of cap 1 and shows gasket 8 and the encircling edgeor wall 11A that retains gasket 8. A circular lateral wall 14 on cap 2retains gasket 8 laterally. As shown, a guide wire 50 passes through oneor more slits 12 in gasket 8. The small eye-shaped defect E is, in thisembodiment, the opening through which bleeding can occur. The slits 12in gasket 8 are the openings through which a secondary device passes andthese seal against the secondary device to help prevent bleeding. Thedistortion of these slits 12 (such as by a thin wire or angiocatheter)is how bleeding occurs with small-diameter secondary devices inrelatively large bore vascular sheaths.

FIG. 3 is a view of the primary seal 20, which as shown is a modifiedO-ring that fits over flange 7 of cap 1. Seal 20 has a proximal end 21and a distal end 22 with respect to the device and a body component 23.Seal 20 has a lumen (not shown) passing therethrough, the lumensufficiently large to allow a secondary device to pass therethrough.Primary seal 20 is configured such that when mounted as part of sheath100, and when compressed, at least part of the lumen constricts tosubstantially seal against the outer surface of a secondary device thatmay be present in the lumen. Seal 20 is preferably injection molded andmade of elastomeric, silicone rubber, although any suitable material ormethod of manufacture may be utilized.

Proximal end 21 of seal 20 has a matching groove 25 and flange 26 toreceive flange 7 of post 6 of cap 1, and post 6 compresses seal 20 whencap 1 is tightened on body 30 although any method or structure may beused to compress seal 20. Body part 23 of seal 20 has a conical distalend 27 that fits into a funnel chamber 31 of body 30 of vascular sheath100. Seal 20 is sufficiently long and preferably has a crease and/ornarrow diameter portion to allow seal 20 to collapse and further reducethe size of its lumen to accommodate small sized secondary devices suchas guide wires or an angio-catheters.

FIG. 4 is a cross-sectional view of a body 30 of the vascular sheath100. Body 30 has a central chamber 31, which during use is preferablyconnected to a pressure line supporting a three-way stopcock forflushing, angiography or pressure monitoring while the sheath in place.Central chamber 31 receives seal 20, as shown in FIG. 6. The distal part31A of chamber 31 is cone or funnel shaped, and has a wall 32 designedto receive the cone shaped distal end 27 (see FIGS. 3 and 6) of seal 20.Distal to chamber 31 is a second chamber 33 that is connected to anopening 34. Opening 34 feeds into a pressure line 35, which in turn isconnected to a three-way stopcock (not shown) for access to the body 30as required for such things as flushing, sampling, angiography via thevascular sheath, and taking hemodynamic measurements.

In this embodiment, external to central chamber 31 is external thread 37that receives inner thread 4 of cap 1, so that cap 1 can be engaged andadvanced or retracted on body 30 thus increasing or decreasing thecompression on seal 20, and thus compressing or opening at least part ofthe lumen of seal 20, when desirable.

A rim 38, which is preferably circular, closes the chambers 31 and 33from the air and connects to external sheath tube 39. Sheath tube 39extends away from body 30 for an appropriate distance so that it canenter the blood vessel a distance required by the procedure beingundertaken, for example, as far as the distal abdominal aorta orapproximately as far as the orifices of one or both renal arteries andall positions in between from an entrance position at the common femoralartery.

The distal end 40 of sheath tube 39 preferably has a chamfered wall 41so that it presents a low profile to produce little damage to the bloodvessel wall when being inserted into the blood vessel. A smallradio-opaque ring (not shown) preferably exists at end 40 so as toprovide the operator with a x-ray visual understanding as to the preciseposition of the distal end of the sheath at all times during theprocedure.

FIG. 5 is a side view of a secondary device, which in this case is anobdurator 41, that may be used with the invention. Obdurator 41 has atapered distal end 41 A, which ends in a tip 41 B. A lumen 42 runs theentire length of obdurator 41 so that obdurator 41 can be passed over aguide wire. Body 43 of obdurator 41 is sized to match with anappropriately sized vascular sheath for a substantially hemostatic fit.In this example, the proximal end 41 of obdurator 44 is fitted with aLuer lock and gripping section 45 for easy grasping and removal orintroduction.

FIG. 6 shows a preferred embodiment of an assembled vascular sheath 100according to the invention. Sheath 100 has guide wire 50 passingtherethrough, and, as shown, seal 20 is uncompressed. As cap 1 isscrewed down on body 30, deformable (or compressible) body 23 of seal 20will collapse to some degree and cone 27 will be pressed inward bypressure exerted by wall 32. At least part of the lumen of seal 20 willbe forced to fully or substantially compress around the guide wire 50.Thus the small eye deformity (see FIG. 2) produced by wire 50 in gasket8 will not leak blood because the blood is sealed by primary seal 20.

In summary, when a large diameter vascular sheath transmits a largesecondary device, bleeding is usually not a major problem. However, toprevent bleeding when the large secondary device has been removed andthe sheath only retains a small secondary device, such as a thin guidewire, the primary seal 20 should be compressed, thus fully orsubstantially compressing the lumen of seal 20 around the outside of thesmaller secondary device to prevent bleeding. If a large secondarydevice needs to be reinserted the primary seal 20 is allowed to relaxthereby opening its lumen.

Also, it is possible to increase the number of disk gaskets (in thepreferred embodiment there is only one, gasket 8) and/or vary the styleof slits from four to three or even one or possibly include a smallsingle circular hole in one or more disk gaskets.

Another benefit that may be derived from the preferred embodiment of theinvention is that it is simple to ship and store, and is fullyassembled. The only step required is to flush the chamber access postvia the side branch, which had a three-way stopcock at its end.

While this invention has been described in terms of its preferredembodiments and various modifications those skilled in the art canappreciate that other modifications can be made without departing formthe spirit and scope of this invention. Other embodiments of theinvention will be apparent to those skilled in the art fromconsideration of the specification and practice of the inventiondisclosed herein. It is intended that the specification and examples beconsidered as exemplary only, with a true scope and spirit of theinvention being indicated by the ultimately-filed claims.

1. A vascular sheath having a manually compressible primary seal, theprimary seal having a lumen therethrough for conforming to the outerdimensions of a secondary device passed through the lumen so as toprevent bleeding while the device is used in a blood vessel.
 2. Thevascular sheath of claim 1 that wherein the primary seal is elastomeric.3. The vascular sheath of claim 1 that wherein the primary seal has aconical end.
 4. The vascular sheath of claim 1 that further includes asecondary seal.
 5. The vascular sheath of claim 4 wherein the secondaryseal is manually movable.
 6. The vascular sheath of claim 5 wherein theprimary seal and secondary seal move in response to the same stimulus.7. The vascular sheath of claim 4 wherein the secondary seal iselastomeric.
 8. The vascular sheath of claim 4 wherein the secondaryseal has one or more slits through which a secondary device may pass. 9.The vascular sheath of claim 8 wherein the secondary seal has two slitsthat form a cross.
 10. The vascular sheath of claim 1 that includes abody and a cap mountable to the body.
 11. The vascular sheath of claim10 wherein the cap may be moved on the body once mounted thereon. 12.The vascular sheath of claim 11 wherein the cap includes a post.
 13. Thevascular sheath of claim 10 that further includes a secondary sealmounted to the cap.
 14. The vascular sheath of claim 13 wherein theprimary seal is mounted on the post.
 15. The vascular sheath of claim 11wherein the primary seal is compressed when the cap is moved in a firstdirection along the body and is relaxed when the cap is moved in asecond direction along the body.
 16. The vascular sheath of claim 10wherein the primary seal is retained in a chamber in the body so that atleast part of the lumen narrows when the primary seal is compressed.